Multiple myeloma with massive ascites fluid--immunophenotypic analysis of myeloma cell and its IL-6-dependent growth

A 75-year-old female was diagnosed as having multiple myeloma (IgG.lambda type. Stage IIA) with plasmacytoma of the head and back in October, 1989. She obtained partial remission by MCNU and MP therapy, but relapsed with massive ascites in January, 1991. VAD therapy was not effective and she died of multiple organ failure on February 23. Her ascites contained a large number of myeloma cells, and the phenotypic analysis and the response to interleukin-6 (IL-6) of these myeloma cells were examined. The myeloma cells were positive for CD33, CD45, CD45RA, CD63, CD71, plasma cell associated antigens such as CD38, PCA-1, BL3, and various kinds of adhesion molecules: CD11a/CD18 (LFA-1), CD29 (VLA-beta 1), CD44 (H-CAM), CD49d (VLA-4), CD54 (ICAM-1), CD56 (N-CAM), CD58 (LFA-3). IL-6 level in the ascites was increased at 91.0pg/ml. The myeloma cells showed an IL-6 dependent growth, which was inhibited by anti-IL-6 antibody (Ab) and anti-IL-6 receptor Ab in vitro. Myeloma cells appearing in ascites have rarely been reported. Our case suggested that IL-6 was a potent growth factor of myeloma cells through an autocrine mechanism in the ascites, and resulted in an aggressive myeloma.